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Continuing Education<br />
Adrian Parnaby-Price, MA, MB, BChir, (Cantab), FRCSEd<br />
The College of<br />
Optometrists<br />
sponsored by<br />
Clinical decision making<br />
in ocular emergencies<br />
The optometrist is <strong>the</strong> first professional contacted by many people<br />
suffering acute ophthalmological conditions. It is, <strong>the</strong>refore,<br />
important that <strong>the</strong>se are recognised and managed effectively,<br />
especially those conditions in which prompt treatment has <strong>the</strong><br />
potential to significantly improve <strong>the</strong> outcome.<br />
The key to management of ocular<br />
problems, and especially in emergencies,<br />
lies in <strong>the</strong> successful diagnosis of <strong>the</strong><br />
condition. Unfortunately, even in<br />
specialist ophthalmic centres, <strong>the</strong><br />
precise diagnosis is not always possible<br />
but recognition of features and patterns<br />
often suggest <strong>the</strong> nature of <strong>the</strong> problem<br />
and are usually enough to guide <strong>the</strong><br />
basic management. Whilst specific areas<br />
are covered in o<strong>the</strong>r parts of this series<br />
(e.g. <strong>the</strong> red eye), <strong>the</strong> aim of this article<br />
is to suggest features of <strong>the</strong> presentation<br />
which will be of help in reaching a<br />
diagnosis upon which management of<br />
specific emergencies can be undertaken.<br />
HISTORY<br />
The limited range of symptoms<br />
pertaining to <strong>the</strong> eye means that most<br />
ophthalmic histories are fairly brief.<br />
Despite this, <strong>the</strong>re is often enough<br />
information to provide clues to <strong>the</strong><br />
underlying pathology or to exclude<br />
o<strong>the</strong>rs. Hence, <strong>the</strong> history of a sudden,<br />
painless loss of vision in an older patient<br />
known to be on medication for high<br />
blood pressure tends to imply a vascular<br />
cause ra<strong>the</strong>r than an inflammatory one.<br />
Pre-existing disease<br />
It is always useful to start <strong>the</strong> history<br />
with a brief question about <strong>the</strong> eyes<br />
before <strong>the</strong> onset of <strong>the</strong> presenting<br />
problem. Previous amblyopia, uveitis or<br />
ocular surgery might influence<br />
subsequent management.<br />
General health<br />
Of particular relevance to ophthalmic<br />
problems are systemic conditions which<br />
are associated with ocular disease,<br />
particularly cardiovascular conditions<br />
(associated with cerebrovascular<br />
accidents and retinal vascular occlusion)<br />
and generalised inflammatory conditions<br />
(associated with uveitis and scleritis).<br />
Many patients are surprisingly reticent<br />
about previous illness which <strong>the</strong>y do not<br />
consider might be related to a problem<br />
with <strong>the</strong> eye and few volunteer a<br />
comprehensive list. It is wise to<br />
formulate a rapid system to work through<br />
this area. A general question to begin<br />
might be - “Apart from your eyes are you<br />
well?” followed by a specific series of<br />
questions to run through disease<br />
associations, for example, “Do you have<br />
high blood pressure or diabetes; have you<br />
had any heart attacks or strokes; have<br />
anything wrong with your joints, bowels,<br />
heart or lungs?”. In cases where <strong>the</strong>re is<br />
little history forthcoming or <strong>the</strong><br />
converse, where a potentially complex<br />
history begins to emerge, it is also wise to<br />
ask for details of any medication. “Do<br />
you take any tablets, pills, puffers,<br />
patches or injections for anything?” -<br />
may rapidly summarise <strong>the</strong> kind of<br />
medical problems which are currently<br />
active and serious enough to require<br />
regular treatment.<br />
PRESENTING COMPLAINT<br />
This can often be summarised concisely<br />
into: 1) whe<strong>the</strong>r <strong>the</strong> vision is affected or<br />
not, what is <strong>the</strong> nature of any visual<br />
problems and what degree of visual<br />
impairment exists; 2) whe<strong>the</strong>r <strong>the</strong> eye is<br />
painful; 3) whe<strong>the</strong>r <strong>the</strong> eye is red; and 4)<br />
<strong>the</strong> speed of onset and duration of any<br />
symptoms (sudden, rapid, slow). This is<br />
actually entirely adequate for <strong>the</strong><br />
assessment of <strong>the</strong> majority of cases and it<br />
is unusual to find ocular problems which<br />
require more detailed questioning or<br />
which, once a painstaking history has<br />
The College of Optometrists has awarded<br />
this article 2 CET credits. There are 12<br />
MCQs with a pass mark of 66%.<br />
been taken, cannot be summarised in<br />
this form. Remember that <strong>the</strong> physical<br />
findings are often more important in<br />
determining <strong>the</strong> management which is<br />
<strong>the</strong> end-point of a consultation, and that<br />
certain points can be reviewed after <strong>the</strong><br />
examination.<br />
Particular features of a history which<br />
might be important in diagnosis and<br />
management are:<br />
Visual acuity<br />
This is often <strong>the</strong> reason for seeking a<br />
consultation and may be described in a<br />
variety of ways by <strong>the</strong> patient. ‘Blurring’<br />
of vision has been use to describe almost<br />
any degree of visual impairment from<br />
distortion with no loss of Snellen acuity<br />
to perception of light. Always try to get<br />
an accurate description of <strong>the</strong><br />
impairment: can <strong>the</strong> patient still read,<br />
watch television, drive a car safely? Is <strong>the</strong><br />
description simply a reduction in acuity<br />
or is <strong>the</strong> patient describing loss of a part<br />
of <strong>the</strong> visual field? The degree of loss may<br />
in itself aid differentiation but large<br />
visual field defects may cause serious<br />
disability and yet still allow a good<br />
Snellen acuity. Occasionally, visual loss is<br />
transient, in which case it is important to<br />
get a detailed description about each<br />
occasion when vision has been lost.<br />
What exactly was <strong>the</strong> patient doing<br />
when <strong>the</strong> vision went and how quickly<br />
did it go; how long was it gone for and<br />
how bad was vision at its worst; how<br />
quickly did it return? For example,<br />
transient occlusion of <strong>the</strong> vertebrobasilar<br />
artery during extreme neck<br />
movements might affect vision only<br />
when driving.<br />
Distortion of vision<br />
Conditions altering <strong>the</strong> anatomy of <strong>the</strong><br />
fovea, such as oedema or sub-retinal<br />
neovascularisation, cause distortion of<br />
<strong>the</strong> retinal photoreceptor position and<br />
this has secondary effects on vision. In<br />
2<br />
APRIL 9 • 1999 OPTOMETRY TODAY
Clinical decision making in ophthalmic emergencies<br />
sponsored by<br />
DISTANCE LEARNING MODULE 1 PART 4<br />
more severe distortions, straight lines<br />
become bent or kinked (door frames are<br />
often among <strong>the</strong> first objects to be noted<br />
as affected). Retinal oedema causes <strong>the</strong><br />
photoreceptors to be displaced apart<br />
from each o<strong>the</strong>r and <strong>the</strong> patient<br />
experiences micropsia where <strong>the</strong> same<br />
size retinal image falls upon fewer<br />
photoreceptors and is, <strong>the</strong>refore,<br />
interpreted as being smaller than in <strong>the</strong><br />
fellow eye. This symptom is, <strong>the</strong>refore,<br />
highly suggestive of foveal pathology and<br />
may be reliably documented with an<br />
Amsler chart.<br />
Pain<br />
This is a feature of a variety of conditions<br />
but, when linked to o<strong>the</strong>r parts of <strong>the</strong><br />
presenting problem, can be important in<br />
establishing a diagnosis. A foreign body<br />
most commonly gives rise to a pricking<br />
sensation and uveitis is more commonly<br />
described as an achy pain with specific<br />
exacerbation in light (photophobia). The<br />
lack of pain might be important as<br />
retinal detachment and vascular events<br />
are painless despite profound visual<br />
disturbance.<br />
Discharge and tearing<br />
Surface problems, such as conjunctivitis<br />
and foreign bodies, cause irritation and<br />
activate defence mechanisms to give rise<br />
to increased secretions. Whilst a watery<br />
discharge in a case of conjunctivitis<br />
might suggest a diagnosis of viral, as<br />
opposed to bacterial, conjunctivitis in<br />
which <strong>the</strong> discharge is more purulent, it<br />
is important to put this feature into its<br />
full clinical context. A watery,<br />
discharging eye is a feature of many more<br />
conditions including severe immune<br />
conditions of <strong>the</strong> sclera in which<br />
perforation of <strong>the</strong> globe is a possibility<br />
and a full history and examination is<br />
imperative.<br />
Flashing lights and floaters<br />
Toge<strong>the</strong>r, <strong>the</strong>se are symptoms of a<br />
posterior vitreous detachment which is<br />
<strong>the</strong> mechanism by which holes are<br />
formed in <strong>the</strong> retina leading to a retinal<br />
detachment. Floaters alone might<br />
indicate inflammation in <strong>the</strong> vitreous<br />
and may be symptomatic only during<br />
reading. Because of <strong>the</strong> paucity of<br />
symptoms from even a large retinal<br />
detachment, <strong>the</strong>se apparently trivial<br />
symptoms should always be treated<br />
seriously as a potential emergency and<br />
mean that a peripheral hole must<br />
specifically be excluded at examination<br />
which cannot be done without pupil<br />
dilation and indirect ophthalmoscopy.<br />
Specific history<br />
Always consider <strong>the</strong> possibility of<br />
trauma, although this is not always<br />
straightforward. Several days can elapse<br />
between metallic foreign bodies entering<br />
<strong>the</strong> eye and <strong>the</strong> onset of symptoms and<br />
some patients (especially children) may<br />
be unwilling or unable to admit to<br />
accident or assault. Chemical injury to<br />
<strong>the</strong> eye must be specifically considered<br />
and excluded. Contact lens use<br />
represents a particular risk for keratitis<br />
and, if lenses are implicated in <strong>the</strong><br />
complaint, it is important to ensure that<br />
<strong>the</strong> daily routine is established,<br />
particularly patterns of wear and<br />
sterilisation methods. All lenses, cases<br />
and solutions should be available for<br />
microbiological examination if possible.<br />
EXAMINATION<br />
Whilst <strong>the</strong> history of <strong>the</strong> problem may<br />
be sketchy or brief, <strong>the</strong> key to diagnosis<br />
is often <strong>the</strong> pattern of pathology based<br />
on <strong>the</strong> findings of <strong>the</strong> clinical<br />
examination and <strong>the</strong> diagnosis may<br />
become clear within moments. Even<br />
quite complex neuro-ophthalmological<br />
conditions may be successfully<br />
diagnosed despite <strong>the</strong> absence of<br />
findings in <strong>the</strong> eye. This part of <strong>the</strong><br />
consultation is, <strong>the</strong>refore, very<br />
important and needs to be undertaken<br />
systematically. Attempts to skip a<br />
complete assessment from <strong>the</strong> outer<br />
eyelids and lashes to <strong>the</strong> retina and discs<br />
will mean that clues may be missed.<br />
Visual acuity<br />
The first part of <strong>the</strong> examination must<br />
be <strong>the</strong> visual acuity in each eye both<br />
unaided and best corrected or using a<br />
pin-hole. Whilst it is occasionally<br />
overlooked in a busy practice, especially<br />
if pathology is clearly identified from <strong>the</strong><br />
outset, it is important to ensure that on<br />
every occasion it is recorded clearly in<br />
any notes. Acuity is sometimes <strong>the</strong> most<br />
useful guide to <strong>the</strong> differentiation<br />
between minor problems and more<br />
serious pathology and is considered a<br />
critical part of any legal analysis of<br />
medical notes.<br />
Colour vision<br />
This is a measure of higher processing<br />
functions but, in severe problems, <strong>the</strong><br />
more useful guide is subjective<br />
sensitivity to red targets. In <strong>the</strong> early<br />
stages of optic nerve disease, <strong>the</strong>re is a<br />
perceived reduction in <strong>the</strong> brightness of<br />
a red target such as a pen top. In<br />
conditions such as acute thyroid eye<br />
disease or orbital cellulitis, in which<br />
<strong>the</strong>re is rapidly increasing orbital<br />
pressures and optic nerve compression,<br />
loss of acuity is a late sign and nerve<br />
swelling occurs even later (by at least 24<br />
hours).<br />
Visual fields<br />
A fur<strong>the</strong>r aid to <strong>the</strong> diagnosis is <strong>the</strong><br />
visual fields. In an emergency setting,<br />
simple patterns are often all that is<br />
required which may be performed with a<br />
red target such as a hat-pin without<br />
complex automated perimetry. The aim<br />
is to identify which part or parts of <strong>the</strong><br />
visual field are affected and it is vital to<br />
ensure that <strong>the</strong> fellow eye is examined as<br />
well. There are a number of classical<br />
patterns of visual field loss but <strong>the</strong><br />
overwhelming majority of patients fit<br />
into one of only a half-dozen or so.<br />
It is simple to consider each field as<br />
consisting of only eight areas (Figure 1).<br />
Each is ‘normal’, ‘impaired’or ‘lost’. Any<br />
findings are, <strong>the</strong>refore, clearer and can<br />
more easily fit a pattern such as<br />
hemianopia, unilateral loss, etc.<br />
The next important features of <strong>the</strong><br />
defect are whe<strong>the</strong>r it extends to central<br />
fixation or not and whe<strong>the</strong>r <strong>the</strong> defects<br />
are centred on <strong>the</strong> blind spot (suggesting<br />
optic nerve disease or larger retinal<br />
vascular problems) or horizontal and<br />
vertical meridia (bilateral mid-line<br />
patterns are generally post-chiasmal and<br />
in <strong>the</strong> brain).<br />
Common patterns and potential<br />
diagnoses include: 1) Hemianopia;<br />
usually homonymous (Figure 2),<br />
suggesting cerebrovascular accident<br />
(CVA, stroke) involving <strong>the</strong> optic<br />
radiations or occipital cortex; may be<br />
bitemporal (Figure 3) suggesting a<br />
lesion at <strong>the</strong> optic chiasm; 2) gross loss<br />
of one field centred on blind spot<br />
(optic nerve involvement such as optic<br />
neuritis or optic nerve tumour) (Figure<br />
4); 3) quadrantanopia (Figure 5) (CVA<br />
in ei<strong>the</strong>r temporal or parietal lobe where<br />
superior and inferior fields have different<br />
pathways); 4) central hemianopia<br />
(Figure 6) (occipital cortex tip lesion);<br />
5) hemianopia sparing central vision<br />
(Figure 7) (occipital cortex lesion with<br />
sparing of occipital tip); and 6)<br />
altitudinal defect (Figure 8) (branch<br />
retinal artery or vein occlusion).<br />
In cases of CVA or tumour-related<br />
disease, <strong>the</strong>re may be o<strong>the</strong>r signs to aid<br />
diagnosis, such as cranial nerve lesions,<br />
which should be considered.<br />
Ocular examination<br />
In an attempt to reach a rapid diagnosis,<br />
it is important not to miss any ocular<br />
APRIL 9 • 1999 OPTOMETRY TODAY 3
sponsored by<br />
Clinical decision making in ophthalmic emergencies<br />
Figure 1<br />
Basic visual fields showing 8<br />
areas and blind spot<br />
Figure 2<br />
Homonymous hemianopia<br />
respecting fixation - CVA<br />
affecting optic radiations<br />
Figure 3<br />
Bitemporal hemianopia<br />
- chiasmal lesion<br />
Figure 4<br />
Loss of one complete visual<br />
field - optic nerve disease<br />
Figure 5<br />
Quadrantanopia<br />
- temporal lobe CVA<br />
Figure 6<br />
Central hemianopia<br />
- occipital cortex tip lesion<br />
Figure 7<br />
Hemianopia sparing central<br />
vision - occipital cortex<br />
sparing tip<br />
Figure 8<br />
Altitudinal defect - inferior<br />
branch vascular occlusion<br />
DISTANCE LEARNING MODULE 1 PART 4<br />
features which may assist diagnosis or<br />
management. It is wise to consider <strong>the</strong><br />
history and symptoms when trying to<br />
identify pathology but, at <strong>the</strong> same time,<br />
each part of <strong>the</strong> eye should be<br />
systematically considered. Even in <strong>the</strong><br />
most dramatic cases, consider first <strong>the</strong><br />
eyelids, <strong>the</strong>n <strong>the</strong> conjunctiva, cornea,<br />
anterior chamber, iris and pupil, vitreous,<br />
retina and disc individually. Always<br />
perform a careful assessment of <strong>the</strong> pupils<br />
for an afferent defect which will indicate<br />
optic nerve disease. A relative afferent<br />
pupillary defect may be present in eyes<br />
with normal vision, although <strong>the</strong> reaction<br />
will not be present when both optic nerves<br />
are equally damaged. The intraocular<br />
pressure (IOP) must be measured before<br />
dilation, even in apparently<br />
straightforward cases. Testing <strong>the</strong> IOP and<br />
<strong>the</strong> pupil are vital in <strong>the</strong> assessment of<br />
patients. For example, in a case of retinal<br />
vascular occlusion, <strong>the</strong> IOP and <strong>the</strong><br />
presence or absence of an afferent<br />
pupillary defect at presentation are key<br />
points in <strong>the</strong> subsequent management. If<br />
<strong>the</strong> patient is already dilated, <strong>the</strong>se cannot<br />
be reliably re-assessed.<br />
In assessing a red eye, <strong>the</strong> green light<br />
filter on <strong>the</strong> slit lamp should be used. This<br />
has <strong>the</strong> effect of bringing <strong>the</strong> red vessels<br />
into much sharper relief by removing<br />
discoloration and allows a much clearer<br />
identification of which layer is injected<br />
(i.e. conjunctiva, episclera or sclera).<br />
Non-ocular signs may exist such as<br />
swollen pre-auricular lymph nodes in viral<br />
conjunctivitis and cranial nerve lesions.<br />
INVESTIGATIONS<br />
These are based on <strong>the</strong> clinical findings<br />
and are often aimed at non-ocular<br />
associations.<br />
Imaging ultrasound, X-rays, MRI<br />
(magnetic resonance imaging) and CT<br />
(computerised tomography) scans are<br />
useful and widely available techniques to<br />
allow detailed examination of non-visible<br />
tissues. B-scan ultrasound is safe and<br />
widely used in ophthalmic departments. It<br />
is most useful in imaging eyes in real-time<br />
for vitreous haemorrhage and scleritis of<br />
<strong>the</strong> posterior globe (which is seen as<br />
thickening and increased signal return).<br />
X-rays are still widely used to identify<br />
sinusitis and breaks in <strong>the</strong> zygoma and<br />
orbital floor following trauma, although<br />
MRI and CT scans are often preferred. CT<br />
scans are currently fairly cheap and widely<br />
available and allow identification of bony<br />
and soft tissue lesions in <strong>the</strong> orbits and<br />
skull. MRI scans tend to be better for<br />
imaging some lesions, particularly<br />
demyelinating lesions (multiple sclerosis<br />
4<br />
APRIL 9 • 1999 OPTOMETRY TODAY
sponsored by<br />
Clinical decision making in ophthalmic emergencies<br />
DISTANCE LEARNING MODULE 1 PART 4<br />
lesions). MRI cannot, however, be used<br />
in those patients with magnetic metals<br />
such as steel in <strong>the</strong> field being examined<br />
as it causes movement and heating of <strong>the</strong><br />
metal. Any suspected foreign body<br />
should be considered when selecting <strong>the</strong><br />
method of imaging.<br />
Microbiology<br />
The isolation of an organism as part of<br />
<strong>the</strong> management of ocular infection is<br />
not always critical if it is mild and<br />
responds to conventional treatment. In<br />
conjunctivitis, most cases are likely to be<br />
self-limiting and conjunctival swabs are<br />
rarely sent. Bacteria can be seen in small<br />
numbers on swabs after brief processing<br />
has been performed to allow a rough<br />
guide as to <strong>the</strong> kind of organisms<br />
involved and, if requested,<br />
microbiological departments can<br />
comment on swabs within hours. Specific<br />
antibiotic sensitivity will not be available<br />
for several days after samples are taken<br />
which is usually too late to influence<br />
initial management.<br />
Wherever possible, samples should be<br />
taken before any antibiotic treatment is<br />
instigated and unpreserved analgesic<br />
drops used as required to allow corneal<br />
scrapes. If treatment is already in<br />
use (including over-<strong>the</strong>-counter<br />
preparations), details should be<br />
forwarded to <strong>the</strong> microbiologist with <strong>the</strong><br />
sample.<br />
Viral swabs have to be transferred<br />
into cultured cells to allow replication<br />
and subsequent identification which<br />
takes several days and prevents rapid<br />
identification. In suspected viral<br />
infections, serology of <strong>the</strong> patient’s<br />
changing antibody levels in response to<br />
<strong>the</strong> infection may be <strong>the</strong> only way to<br />
identify <strong>the</strong> virus.<br />
Particular cases, where identification<br />
of <strong>the</strong> organism is crucial, include<br />
endophthalmitis and acanthamoeba<br />
keratitis where prolonged and intensive<br />
treatment will be required with<br />
implications for <strong>the</strong> prognosis. In<br />
contact-lens related infection, <strong>the</strong> lenses,<br />
case and cleaning solutions should be<br />
sent for analysis.<br />
Blood tests<br />
Many of <strong>the</strong>se are for systemic<br />
associations of ocular pathology and are<br />
focused about specific diagnoses. In<br />
arterial occlusion, <strong>the</strong> most important<br />
differential diagnosis is between<br />
inflammatory and non-inflammatory<br />
causes and an ESR (erythrocyte<br />
sedimentation rate) and CRP<br />
(C-reactive protein) level is mandatory<br />
(both are non-specific measures of<br />
generalised inflammatory activity but<br />
not diagnostic of specific conditions in<br />
<strong>the</strong>mselves). Vascular occlusions<br />
generally require blood counts for<br />
clotting predispositions such as excess<br />
haemoglobin and platelet levels,<br />
inflammatory and clotting diseases and<br />
serum markers for a<strong>the</strong>rosclerosis<br />
(cholesterol and fat levels). Acute<br />
proptosis requires investigations centred<br />
on inflammatory conditions but<br />
especially for antibodies implicated in<br />
thyroid disease (<strong>the</strong> most common cause<br />
of both unilateral and bilateral<br />
proptosis).<br />
TREATMENT<br />
Comprehensive and detailed<br />
management of individual conditions is<br />
beyond <strong>the</strong> scope of this article but many<br />
are covered in o<strong>the</strong>r articles in <strong>the</strong> CPD<br />
series. The following are some of <strong>the</strong><br />
more common conditions, particularly<br />
those that are potentially serious or in<br />
which effective management may<br />
improve <strong>the</strong> outcome.<br />
VASCULAR EMERGENCIES<br />
Central and branch<br />
retinal artery occlusion<br />
The most important investigations once<br />
diagnosis has been made are <strong>the</strong> ESR<br />
and CRP (see above). On this basis,<br />
arterial occlusion is presumed to be<br />
ei<strong>the</strong>r non-arteritic (thrombo-embolic in<br />
origin) or arteritic (inflammatory in<br />
origin).<br />
Non-arteritic CRAO (Figure 9)<br />
Treatment can be very effective if<br />
administered within 24 hours of onset<br />
and hinges around attempts to dislodge<br />
<strong>the</strong> embolus to <strong>the</strong> retinal periphery<br />
where loss of blood supply will cause<br />
limited damage to <strong>the</strong> vision. This is<br />
achieved in <strong>the</strong> first instance by globe<br />
massage in much <strong>the</strong> same way as a<br />
plunger is used on a blocked domestic<br />
pipe. The patient closes <strong>the</strong> eye and two<br />
fingers are used to press on <strong>the</strong> closed<br />
lids firmly and continuously for around a<br />
minute to build up <strong>the</strong> intraocular<br />
pressure. The fingers are <strong>the</strong>n suddenly<br />
removed to drop <strong>the</strong> IOP rapidly and<br />
dislodge <strong>the</strong> embolus. The process is<br />
repeated at one-minute intervals and<br />
can be continued en-route to <strong>the</strong> nearest<br />
ophthalmic unit. Some authorities<br />
advocate a firm rubbing of <strong>the</strong> closed eye<br />
to achieve a similar fluctuation in IOP.<br />
Steps are subsequently taken to reduce<br />
<strong>the</strong> pressure opposing arterial blood flow<br />
Figure 9<br />
Central retinal artery occlusion with cherry red<br />
spot. Note a cilioretinal artery preserving a<br />
small area of normal retina adjacent to <strong>the</strong><br />
disc for comparison<br />
(<strong>the</strong> greatest and most flexible<br />
component of which is, again, <strong>the</strong> IOP)<br />
and help to push <strong>the</strong> embolus fur<strong>the</strong>r<br />
along <strong>the</strong> vessel. IOP may be reduced by<br />
pharmacological means including<br />
conventional glaucoma medication and<br />
acetazolamide and can be reduced by<br />
breathing higher levels of carbon<br />
dioxide. This causes venous dilatation<br />
with a fall in back-pressure and this is<br />
most easily achieved by asking <strong>the</strong><br />
patient to brea<strong>the</strong> in and out of a paper<br />
bag. IOP may be most rapidly and<br />
efficiently dropped by anterior chamber<br />
paracentesis. This entails sitting <strong>the</strong><br />
patient on a slit lamp and anaes<strong>the</strong>tising<br />
<strong>the</strong> eye with topical drops before a fine<br />
needle mounted on a syringe without a<br />
plunger is inserted into <strong>the</strong> anterior<br />
chamber through <strong>the</strong> limbus. 0.1-0.3ml<br />
of aqueous is removed before <strong>the</strong> needle<br />
is withdrawn and, because fluid is not<br />
compressible, IOP falls profoundly.<br />
Management in <strong>the</strong> longer term is to<br />
maintain a low IOP and to treat<br />
underlying risk factors such as<br />
a<strong>the</strong>rosclerosis, hypertension and, in<br />
some cases, oral anti-coagulation with<br />
aspirin or warfarin.<br />
Arteritic (inflammatory) CRAO<br />
Whilst producing a similar ocular picture<br />
to embolic disease, inflammation of <strong>the</strong><br />
arterial walls also produces retinal artery<br />
occlusion. This is a process similar to<br />
arteritic anterior ischaemic optic<br />
neuropathy (see over).<br />
Anterior ischaemic optic neuropathy<br />
This is <strong>the</strong> occlusion of <strong>the</strong> posterior<br />
ciliary arteries causing infarction of <strong>the</strong><br />
optic nerve head. Visual loss is rapid and<br />
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Figure 10<br />
New vessels at <strong>the</strong> optic disc in severe<br />
diabetic retinopathy<br />
Figure 11<br />
Vitreous haemorrhage from disc new vessels<br />
profound and irreversible with an early<br />
relative afferent pupil defect. Although<br />
anecdotal reports exist of partial visual<br />
loss and of some recovery of vision, this<br />
is unusual and a history of intermittent<br />
loss of vision should suggest a different<br />
diagnosis. As in CRAO, two variants are<br />
recognised, non-arteritic and arteritic.<br />
Non-arteritic AION<br />
This is probably a variant of CRAO with<br />
a<strong>the</strong>rosclerosis as <strong>the</strong> underlying<br />
associated or causative pathology.<br />
Management is similar to CRAO with<br />
reduction in IOP, aspirin and anticoagulation<br />
as <strong>the</strong>rapeutic options in <strong>the</strong><br />
acute phase and management of<br />
a<strong>the</strong>rosclerotic associations in <strong>the</strong><br />
follow-up period.<br />
Arteritic AION<br />
(and arteritic CRAO - see above)<br />
This is most commonly associated with<br />
temporal arteritis. This condition almost<br />
exclusively affects <strong>the</strong> over-70s and cases<br />
under <strong>the</strong> age of 55 are rare. Temporal<br />
arteritis is associated with polymyalgia<br />
rheumatica in which <strong>the</strong>re is usually a<br />
long history of non-specific illness,<br />
weight loss, pain, wasting and weakness<br />
of muscles of <strong>the</strong> upper legs, upper arms<br />
and shoulders with difficulty in raising<br />
<strong>the</strong> arms above <strong>the</strong> shoulders to brush<br />
<strong>the</strong> hair. Temporal arteritis also causes a<br />
tender scalp and jaw claudication<br />
(progressive weakness and pain on<br />
chewing). Blood tests characteristically<br />
reveal a very high ESR and CRP and<br />
biopsy of <strong>the</strong> temporal artery provides<br />
typical changes of inflammation in <strong>the</strong><br />
walls of <strong>the</strong> vessel. Surgical biopsy of a<br />
section of <strong>the</strong> temporal artery is <strong>the</strong> most<br />
accurate diagnostic test of temporal<br />
arteritis. Initial management is with very<br />
high doses of intravenous steroids and<br />
maintenance on oral steroids at a high<br />
dose for several weeks with a gradual<br />
reduction over not less than 1-2 years.<br />
Few reports exist of any recovery of vision<br />
in <strong>the</strong> affected eye despite rapid<br />
treatment, but <strong>the</strong> aim is to preserve <strong>the</strong><br />
second eye and prevent spread to o<strong>the</strong>r<br />
arteries such as <strong>the</strong> basilar artery in <strong>the</strong><br />
brain with secondary, usually fatal<br />
cerebrovascular accident. Generalised<br />
symptoms of polymyalgia rheumatica and<br />
temporal arteritis rapidly improve on<br />
treatment.<br />
Central and branch<br />
retinal vein occlusion<br />
The acute management of vein<br />
occlusions is aimed at reducing <strong>the</strong><br />
tendency to form thrombus and to<br />
increase venous drainage from <strong>the</strong> retina.<br />
Acutely investigations need to exclude or<br />
correct high levels of haemoglobin or<br />
platelets and any fluid deficit. O<strong>the</strong>r<br />
factors which need to be specifically<br />
addressed are those tending to thrombus<br />
including oral contraceptive use in<br />
women and o<strong>the</strong>r conditions affecting<br />
clotting. Current opinion is divided as to<br />
whe<strong>the</strong>r anti-coagulation is of benefit in<br />
<strong>the</strong> acute phase as <strong>the</strong> retinal picture is<br />
haemorrhagic and could potentially be<br />
worsened. After three months oral<br />
aspirin, which selectively reduces platelet<br />
activity, is widely used although <strong>the</strong> dose<br />
at which benefit may occur is uncertain.<br />
In <strong>the</strong> longer term, trials to reduce<br />
haemoglobin levels by isovolaemic<br />
haemodilution in patients fulfilling<br />
certain criteria have produced scant<br />
evidence that this may help but this<br />
technique is not widely used.<br />
Vitreous haemorrhage<br />
This usually presents with a painless loss<br />
of vision although it may be associated<br />
with ocular trauma. There is usually a<br />
specific cause for <strong>the</strong> haemorrhage which<br />
include new vessels from diabetes<br />
(Figure 10 and 11), an old retinal<br />
vascular occlusion and from posterior<br />
vitreous detachment with avulsion of a<br />
retinal vessel. Whilst <strong>the</strong> haemorrhage<br />
will clear spontaneously with time, <strong>the</strong><br />
biggest problem arises from <strong>the</strong> potential<br />
for progression of o<strong>the</strong>r pathology. All<br />
cases should be managed as a potential<br />
retinal detachment identified by<br />
ultrasound of <strong>the</strong> eye or by indirect<br />
ophthalmoscopy. Such cases may need<br />
vitrectomy to clear <strong>the</strong> haemorrhage<br />
before proceeding to management of<br />
associated problems.<br />
Cerebrovascular accident<br />
(CVA, stroke)<br />
This is <strong>the</strong> result of problems with <strong>the</strong><br />
blood supply to <strong>the</strong> brain and is usually<br />
<strong>the</strong> result of a<strong>the</strong>rosclerosis. There are<br />
two main types: ischaemic, in which<br />
vessels ei<strong>the</strong>r tend to occlude (with loss<br />
of <strong>the</strong> blood supply to <strong>the</strong> brain); and<br />
haemorrhagic when vessels bleed into<br />
<strong>the</strong> tissue of <strong>the</strong> brain. A third type is <strong>the</strong><br />
transient form in which symptoms<br />
resolve within 24 hours and which are<br />
considered to be due to small emboli<br />
(transient ischaemic attacks - TIAs).<br />
The exact clinical picture depends upon<br />
<strong>the</strong> site of <strong>the</strong> problem but can produce a<br />
bewildering variety of symptoms and<br />
signs. Presentations include single or<br />
multiple nerve palsies of any of <strong>the</strong><br />
ocular and associated nerves and<br />
particular patterns of visual field loss<br />
including hemianopias, quadrantanopias<br />
and, occasionally, loss of only small parts<br />
of field around fixation or central vision<br />
(due to lesions at <strong>the</strong> tip of <strong>the</strong> occipital<br />
lobe). Many neurological problems may<br />
be apparent from a good history and<br />
clinical examination (especially of visual<br />
fields) and require urgent investigation<br />
and management firstly to reduce risk<br />
factors for CVA and also to exclude<br />
o<strong>the</strong>r causes of neurological damage such<br />
as intracranial tumours, abscesses and<br />
inflammatory conditions involving <strong>the</strong><br />
brain.<br />
TRAUMA<br />
Most traumatic conditions will require<br />
specific surgery to correct <strong>the</strong> injury but<br />
in all cases of trauma, <strong>the</strong> principal<br />
maxim is to fully elucidate <strong>the</strong> nature<br />
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and extent of any injury by adequate<br />
examination and to fully plan surgery or<br />
o<strong>the</strong>r management. In unco-operative<br />
patients (particularly in children) a<br />
general anaes<strong>the</strong>tic may be required. In<br />
o<strong>the</strong>r cases, unpreserved anaes<strong>the</strong>tic<br />
drops are considered safe following<br />
penetrating injury (and are used without<br />
retinal toxicity in ocular irrigating fluids<br />
during surgery) and may be used as<br />
required to facilitate examination. The<br />
risk of infection after penetrating injury<br />
is actually surprisingly small but <strong>the</strong><br />
administration of systemic antibiotics<br />
prior to surgery is <strong>the</strong> main adjunct.<br />
Topical antibiotics appear to convey no<br />
significant effect on reducing<br />
endophthmitis.<br />
Corneal abrasion<br />
This is excruciatingly painful in younger<br />
patients with symptoms out of<br />
proportion to <strong>the</strong> apparent injury.<br />
Always consider more serious injury and<br />
possible globe penetration during<br />
examination. Dilation of <strong>the</strong> pupil is an<br />
extremely effective analgesic and many<br />
authorities commend pressure patching<br />
until re-epi<strong>the</strong>lialisation has occurred<br />
with consequent reduction in pain. Do<br />
not patch an eye unless it is taped shut or<br />
a lubricated gauze is placed next to <strong>the</strong><br />
eye in case an abrasion is caused by <strong>the</strong><br />
dressing. Many patients find a pressure<br />
dressing uncomfortable and consider an<br />
unpatched eye preferable and use ice<br />
packs with some relief. Rarely <strong>the</strong><br />
epi<strong>the</strong>lium fails to heal in which case<br />
deliberate removal of <strong>the</strong> epi<strong>the</strong>lium to<br />
allow a fresh attempt is usually effective.<br />
Recurent corneal erosion<br />
This may follow an abrasion, sometimes<br />
months later, and presents typically with<br />
a patient awaking during REM sleep.<br />
Rapid eye movement is thought to<br />
spontaneously abrade <strong>the</strong> corneal<br />
epi<strong>the</strong>lium with similar extreme pain,<br />
although it is usually on a smaller scale<br />
and has often healed by <strong>the</strong> time <strong>the</strong><br />
patient is examined on a slit lamp with<br />
obvious diagnostic problems. Most cases<br />
resolve with <strong>the</strong> use of topical lubricants<br />
applied last thing at night or epi<strong>the</strong>lial<br />
debridement.<br />
Chemical injury<br />
Chemical injury requires an immediate<br />
response with removal of <strong>the</strong> material<br />
with forceps if appropriate followed by<br />
irrigation with saline or water. Topical<br />
anaes<strong>the</strong>sia should be used as required to<br />
permit examination and irrigation<br />
performed even if penetration is<br />
suspected. Do not accept any history of<br />
previous irrigation at <strong>the</strong> scene of <strong>the</strong><br />
accident as satisfactory - ALWAYS<br />
REPEAT IT YOURSELF<br />
IMMEDIATELY - 30 minutes with 1-2<br />
litres of saline or water is usually required<br />
to produce satisfactory results and <strong>the</strong><br />
lids must be everted to ensure that<br />
subtarsal remnants are not missed. Even<br />
where eyewash is available, it is only<br />
rarely in sufficient quantity to be<br />
effective. pH should be checked with<br />
particular caution being exercised if<br />
alkali injury is suspected (high pH) as<br />
alkali rapidly enters <strong>the</strong> anterior chamber<br />
with signs of ischaemia manifest as closed<br />
vessels at <strong>the</strong> limbus and corneal<br />
epi<strong>the</strong>lial loss.<br />
If syn<strong>the</strong>tic riot-control agents such<br />
as CS, mace or tear gas have been used,<br />
particular care must be exercised not to<br />
allow contact of health workers with <strong>the</strong><br />
clo<strong>the</strong>s of <strong>the</strong> victim as any remaining<br />
agent can be transmitted with disastrous<br />
results. Again, topical anaes<strong>the</strong>tic as<br />
required, ocular examination to<br />
determine injury followed by copious<br />
irrigation with water or saline, remains<br />
<strong>the</strong> recommended treatment. Pain,<br />
inflammation and secondary infection<br />
are treated with topical mydriatics,<br />
steroids and antibiotics as required. As<br />
soon as possible, ensure that no o<strong>the</strong>r<br />
ocular injury exists in conjunction.<br />
INFLAMMATORY AND<br />
ALLERGIC EMERGENCIES<br />
Hayfever and atopic disease<br />
Whilst not considered a serious<br />
condition, mild forms of allergy in <strong>the</strong> eye<br />
are common and constitute a significant<br />
workload to some practitioners. They are<br />
often associated with o<strong>the</strong>r allergies such<br />
as asthma and eczema. Severe forms are<br />
difficult to diagnose as <strong>the</strong>y may resemble<br />
more severe inflammatory conditions,<br />
particularly viral keratoconjunctivitis<br />
with corneal infiltrates but <strong>the</strong> absence of<br />
a swollen pre-auricular lymph node is an<br />
important diagnostic feature. Follicles<br />
(which are usually swollen to form ‘grains<br />
of rice’ in <strong>the</strong> tarsal conjunctiva in <strong>the</strong><br />
acute phase) and more superficial<br />
injection over <strong>the</strong> globe are also features<br />
of allergy. In extreme cases, lacrimation<br />
occurs under <strong>the</strong> conjunctiva with<br />
chemosis (Figure 12). Always check <strong>the</strong><br />
visual acuity and warn <strong>the</strong> patient to<br />
re-attend if symptoms persist or worsen.<br />
Figure 12<br />
Conjunctival chemosis in acute allergic eye disease<br />
Figure 13<br />
Acute iritis showing perilimbal injection<br />
Acute symptoms are best controlled with<br />
ice packs and topical antihistamines and<br />
mast-cell stabilisers with topical steroids<br />
reserved for more severe cases.<br />
Anterior uveitis<br />
This has several clinical appearances<br />
with variable amounts of fibrin (flare)<br />
and aggregations of leucocytes in <strong>the</strong><br />
aqueous (cells) (Figure 13). The history<br />
is usually of gradual increase in irritation,<br />
redness, photophobia and reduction in<br />
acuity. This can be over several days,<br />
weeks or may be of only a few hours. The<br />
long-term complications of acute<br />
anterior uveitis stem from <strong>the</strong> deposition<br />
of fibrin and subsequent scar formation<br />
in <strong>the</strong> trabecular meshwork to produce<br />
glaucoma. Adhesions between <strong>the</strong> iris<br />
and <strong>the</strong> anterior lens capsule produce<br />
synechiae with pupil distortion and<br />
obstruction of <strong>the</strong> flow of aqueous<br />
through <strong>the</strong> pupil with a risk of pupilblock<br />
glaucoma. Anterior uveitis,<br />
<strong>the</strong>refore, needs to be suppressed rapidly<br />
before <strong>the</strong>se changes become established.<br />
Firstline treatment is with frequent dose<br />
topical steroids and dilation of <strong>the</strong> pupil.<br />
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Figure 14<br />
Mutton fat keratic precipitates in granulomatous<br />
uveitis. Associated systemic diseases need to be<br />
excluded<br />
In cases with a high fibrinous<br />
component, or in which synechiae have<br />
already formed, steroids and mydriatics<br />
may be given as a sub-conjunctival<br />
injection to maximise dosage. Intraocular<br />
pressure rises are usually managed with<br />
conventional topical glaucoma <strong>the</strong>rapy.<br />
As <strong>the</strong> uveitis comes under control,<br />
treatment is tapered but may need to be<br />
continued for weeks or months to avoid<br />
recurrences, which are relatively<br />
common. Unresponsive cases are<br />
infrequent but, occasionally, require<br />
systemic treatment with<br />
immunosuppressive drugs including<br />
steroids, azathioprine and cyclosporin<br />
(potent suppressers of T-lymphocyte<br />
activity, <strong>the</strong> leucocytes thought to<br />
control <strong>the</strong> underlying inflammatory<br />
process). Uncomplicated cases which<br />
respond rapidly to topical treatment are<br />
not usually extensively investigated but<br />
mutton-fat keratic precipitates of<br />
leucocytes (which are larger and more<br />
greasy in appearance) are particularly<br />
suggestive of an associated inflammatory<br />
condition (Figure 14).<br />
Posterior uveitis<br />
This tends to present with a more<br />
gradual onset than anterior uveitis with a<br />
gradual, painless impairment of vision<br />
and, in particular, <strong>the</strong> formation of<br />
floaters. It is potentially more serious as it<br />
may have been active longer prior to<br />
diagnosis and <strong>the</strong> retina is frequently<br />
directly involved with permanent visual<br />
impairment. Signs of active inflammation<br />
are chiefly <strong>the</strong> finding of small deposits of<br />
leucocytes in <strong>the</strong> vitreous and cases<br />
usually require prolonged and intensive<br />
management with systemic<br />
immunosuppressive drugs. There is a<br />
high incidence of associated diseases<br />
including Behçet’s disease, sarcoidosis<br />
and idiopathic retinal vasculitis which<br />
need to be considered.<br />
Episcleritis<br />
This presents with discomfort or usually<br />
mild pain in a watery red eye. There is<br />
usually no impairment of vision and<br />
injection is in a fairly discrete area with<br />
dilation of <strong>the</strong> finer, more superficial<br />
episcleral vessels and a slight blue-purple<br />
hue to <strong>the</strong> area. Although attacks are<br />
self-limiting and resolve without<br />
sequelae, topical steroids and oral<br />
flurbiprofen control symptoms and<br />
shorten attacks. A similar condition is an<br />
inflamed pingueculum in which an<br />
episcleitis-like condition is centered on a<br />
pre-existing pingueculum. This responds<br />
to similar treatment and also resolves<br />
without sequelae. Recurrence is common<br />
in both conditions.<br />
Scleritis<br />
This is usually painful and can be<br />
localised to a small, discrete area or be<br />
more extensive. Vision is usually<br />
unaffected and <strong>the</strong> condition is<br />
associated with o<strong>the</strong>r immune disorders<br />
including rheumatoid arthritis. A<br />
variant is posterior scleritis in which<br />
severe pain can be a feature in an eye<br />
which is not red. Secondary oedema may<br />
induce retinal changes with visual<br />
symptoms and occasionally proptosis or<br />
even optic nerve compression. Imaging<br />
with ultrasound, MRI or CT scan reveals<br />
thickening of <strong>the</strong> sclera. Treatment is<br />
systemic with oral non-steroidal antiinflammatory<br />
drugs (particularly<br />
Flurbiprofen and indomethacin). In<br />
severe cases oral and intravenous<br />
steroids and o<strong>the</strong>r immunosuppressives<br />
may be required.<br />
Optic neuritis<br />
Inflammation of <strong>the</strong> optic nerve is<br />
usually a part of a demyelinating disease<br />
(of which multiple sclerosis is <strong>the</strong> most<br />
common form). The visual loss occurs<br />
over a few days and is usually profound.<br />
It is associated in <strong>the</strong> initial stages with a<br />
reduction in sensitivity to red objects and<br />
an afferent pupil defect, and may be<br />
associated with active lesions elsewhere<br />
including <strong>the</strong> fellow optic nerve. If <strong>the</strong><br />
focal lesion is not close to <strong>the</strong> optic nerve<br />
head, <strong>the</strong>re may be no disc swelling or<br />
o<strong>the</strong>r signs of disease. Treatment is<br />
limited with high dose intravenous<br />
steroids used in severe cases but <strong>the</strong>se<br />
seem to offer little or no long-term<br />
benefit.<br />
INFECTIVE CONDITIONS<br />
Conjunctivitis<br />
Bacterial conjunctivitis may be identified<br />
by its mucoid or purulent discharge with<br />
little effect on <strong>the</strong> visual acuity. Most<br />
cases are self-limiting although cases<br />
caused by Neisseria or Chlamydia may be<br />
persistent and require systemic<br />
treatment for associated sites of infection<br />
(most commonly <strong>the</strong> genito-urinary<br />
tract). Viral conjunctivitis is associated<br />
with a watery discharge and follicles in<br />
<strong>the</strong> conjunctiva of <strong>the</strong> eyelids. A swollen<br />
pre-auricular lymph node (just in front<br />
of <strong>the</strong> ear on <strong>the</strong> affected side) is a<br />
common finding. Vision may be affected<br />
if <strong>the</strong> cornea is also involved, often in a<br />
characteristic pattern of sub-epi<strong>the</strong>lial<br />
opacities (e.g. in adenoviral<br />
keratoconjunctivitis). Most are thought<br />
to be spread by droplets from <strong>the</strong> nose<br />
and throat of infected individuals and<br />
epidemics are common. There is no<br />
specific treatment for viral infections<br />
(o<strong>the</strong>r than for herpes virus) and disease<br />
can continue for several weeks or even<br />
months. Whilst symptoms can be<br />
controlled by treatment with topical<br />
steroids, this is thought to prolong <strong>the</strong><br />
recovery time and is usually reserved for<br />
particularly severe cases. Topical<br />
antibiotics are often prescribed to reduce<br />
<strong>the</strong> risk of secondary bacterial infection<br />
but evidence for <strong>the</strong>ir effectiveness is<br />
poor.<br />
Keratitis (including<br />
acanthamoeba, bacterial<br />
and herpetic keratitis)<br />
This is characterised by pain, corneal<br />
infiltrate and epi<strong>the</strong>lial defect. The<br />
keratitis may be infectious (associated<br />
with contact lens use) although o<strong>the</strong>r<br />
conditions, including autoimmune<br />
disease, can cause severe keratitis.<br />
Whilst certain patterns of keratitis are<br />
diagnostic (such as herpetic),<br />
microbiological analysis of any infection<br />
from swabs and corneal scrapes guides<br />
subsequent intensive antibiotic<br />
treatment. Topical and/or systemic<br />
immunosuppression is usually required<br />
to control inflammatory causes.<br />
Orbital cellulitis,<br />
sinusitis and dacrocystitis<br />
Bacterial infections in sites adjacent to<br />
<strong>the</strong> orbit may lead to secondary infection<br />
and patients may present with proptosis<br />
and reduced ocular movements.<br />
Because of <strong>the</strong> associated swelling, <strong>the</strong>re<br />
is a risk that orbital pressure will rise with<br />
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optic nerve compression (see above). A<br />
broad-spectrum antibiotic in high dose<br />
is required but care must be exercised in<br />
dacrocystitis - if <strong>the</strong> sac is lanced or<br />
bursts through <strong>the</strong> skin of <strong>the</strong> cheek, a<br />
fistula may form requiring surgical<br />
correction.<br />
Herpes zoster (shingles)<br />
This is caused by reactivation of <strong>the</strong><br />
varicella-zoster virus (which causes<br />
chickenpox) which remains dormant in<br />
a sensory nerve root. Reactivation<br />
occurs in response to alteration in <strong>the</strong><br />
immune system with effects in <strong>the</strong><br />
anatomy supplied by <strong>the</strong> particular<br />
nerve involved. Globe and lid sensation<br />
is served by <strong>the</strong> ophthalmic and<br />
maxillary branches of <strong>the</strong> fifth cranial<br />
nerve and early symptoms are of altered<br />
sensation or pain over <strong>the</strong> area<br />
involved. Swelling and pain may<br />
precede <strong>the</strong> typical skin rash which<br />
produces weeping pustules and appears<br />
around four to seven days after initial<br />
symptoms. Conjunctivitis of<br />
predominantly <strong>the</strong> upper or lower lid,<br />
keratitis and scleritis are common<br />
features although intraocular<br />
involvement is not common. Entry to<br />
<strong>the</strong> eye requires involvement of a<br />
sensory branch, <strong>the</strong> naso-ciliary nerve.<br />
The presence of rash at <strong>the</strong> tip of <strong>the</strong><br />
nose (Hutchinson’s sign) should raise<br />
suspicions and suggest more frequent<br />
review as <strong>the</strong> uveitis produced can be<br />
insidious and asymptomatic until fairly<br />
advanced. Treatment is with specific<br />
anti-viral drugs to limit <strong>the</strong> replication<br />
of virus and shorten <strong>the</strong> attack. There is<br />
also some suggestion that prompt antiviral<br />
<strong>the</strong>rapy can reduce <strong>the</strong> incidence<br />
of post-herpetic neuralgia. In cases<br />
without intraocular involvement,<br />
recovery is straightforward but<br />
intraocular inflammation requires<br />
intensive topical treatment (see anterior<br />
uveitis) and is prone to relapse. Most<br />
cases require at least nine months of<br />
topical steroid drops.<br />
RETINAL AND DISC CONDITIONS<br />
Retinal detachment<br />
This often presents late and advanced<br />
with extensive peripheral field loss as it<br />
is not until <strong>the</strong>re is loss of macular<br />
function that <strong>the</strong> patient notices a<br />
definite symptom. Management is to<br />
close any retinal holes and relieve<br />
vitreous traction on <strong>the</strong> retina to allow<br />
re-attachment by external buckling of<br />
<strong>the</strong> sclera or by vitrectomy.<br />
Macular oedema<br />
This is a feature of a number of<br />
conditions including diabetes, various<br />
inflammatory conditions of <strong>the</strong> retina,<br />
scleritis and central serous<br />
chorioretinopathy. This causes a<br />
variable degree of visual distortion and<br />
loss of acuity. Treatment relates to <strong>the</strong><br />
diagnosis and may require laser<br />
photocoagulation of areas of capillary<br />
leakage.<br />
Hypertensive retinopathy<br />
Treatment is directed at <strong>the</strong><br />
hypertension or <strong>the</strong> cause of<br />
hypertension but cases are often those in<br />
which hypertension is secondary to o<strong>the</strong>r<br />
diagnoses and difficult to manage. The<br />
ocular problems tend to predispose<br />
towards a picture of vascular occlusion<br />
and disc swelling (Figure 15) but<br />
resolve when <strong>the</strong> blood pressure lowers.<br />
Unfortunately, <strong>the</strong> more severe cases<br />
often have a poor prognosis with<br />
multiple organ failure.<br />
Swollen optic discs - optic neuritis,<br />
intracranial hypertension<br />
Swollen discs may be due to a number of<br />
causes including optic nerve head drusen<br />
but, in <strong>the</strong> presence of visual reduction,<br />
headache and o<strong>the</strong>r symptoms, need to<br />
be considered as potentially due to a<br />
more serious pathological process. An<br />
MRI or CT of <strong>the</strong> brain and orbits will be<br />
required to exclude lesions of <strong>the</strong> optic<br />
nerves such as meningiomas,<br />
demyelinating disease or lesions in <strong>the</strong><br />
ventricular system of <strong>the</strong> brain. Lumbar<br />
puncture is often required to establish<br />
<strong>the</strong> pressure of cerebrospinal fluid and to<br />
examine it for <strong>the</strong> presence of<br />
inflammatory cells or proteins.<br />
OTHER CONDITIONS<br />
Glaucoma<br />
Acute closed angle glaucoma causes<br />
damage to <strong>the</strong> optic nerve and <strong>the</strong>re is a<br />
significant risk of secondary vascular<br />
occlusion. While intraocular pressure is<br />
high, little or no topical medication will<br />
enter <strong>the</strong> eye and intravenous or oral<br />
acetazolamide is required to cause initial<br />
pressure reduction. Pilocarpine and<br />
o<strong>the</strong>r topical glaucoma treatments are<br />
Figure 15<br />
Swollen optic disc in acute hypertensive<br />
retinopathy<br />
used <strong>the</strong>reafter. In <strong>the</strong> longer term, YAG<br />
or argon laser iridotomy or surgical<br />
iridectomy is <strong>the</strong> treatment of choice to<br />
maintain low pressure with a few<br />
patients requiring more extensive<br />
surgery because of irreversible damage to<br />
<strong>the</strong> angle. Treatment may be delayed<br />
until intraocular pressure is controlled by<br />
medical treatment, as oedema can make<br />
<strong>the</strong> cornea opaque to lasers and require<br />
excessive power to permit treatment.<br />
Thyroid eye disease<br />
Thyroid eye disease is generally a<br />
chronic problem in which <strong>the</strong> orbital fat<br />
swells and extraocular muscles fibrose.<br />
This can present with acute proptosis<br />
but less often presents as visual loss<br />
resulting from optic nerve compression.<br />
The condition is rare and requires<br />
systemic immunosuppression, X-ray<br />
treatment and, occasionally, surgery to<br />
<strong>the</strong> orbit to release <strong>the</strong> pressure.<br />
CONCLUSION<br />
The key to <strong>the</strong> optimum management of<br />
ocular emergencies lies in a careful<br />
assessment of <strong>the</strong> features of <strong>the</strong><br />
condition to suggest <strong>the</strong> general nature<br />
of <strong>the</strong> problem. This, in turn, will guide<br />
<strong>the</strong> initial management to allow<br />
appropriate investigations and basic<br />
treatment.<br />
ABOUT THE AUTHOR<br />
Adrian Parnaby-Price is a Fellow in Ocular Immunology at<br />
St Thomas’s Hospital, London, and a Specialist Registrar in<br />
Ophthalmology in <strong>the</strong> South-East Thames Region.<br />
APRIL 9 • 1999 OPTOMETRY TODAY 9
Multiple choice questions<br />
Clinical decision making in ophthalmic emergencies<br />
Please note <strong>the</strong>re is only ONE correct answer. An answer return form is included in this issue.<br />
It should be completed and returned to: CPD Initiatives (CDM4), <strong>Optometry</strong> <strong>Today</strong>,<br />
Victoria House, 178-180 Fleet Road, Fleet, Hampshire GU13 8DA, by May 5, 1999.<br />
1. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
Vitreous haemorrhage:<br />
a. may be associated with retinal<br />
detachment<br />
b. may be associated with posterior<br />
vitreous detachment<br />
c. may be caused by diabetic<br />
neovascular proliferation<br />
d. always causes a relative afferent<br />
pupillary defect<br />
2. Which one of <strong>the</strong> following<br />
statements is correct?<br />
A watery eye and palpable<br />
pre-auricular lymph node<br />
is a common feature of:<br />
a. adenoviral keratoconjunctivitis<br />
b. episcleritis<br />
c. chlamydial conjunctivitis<br />
d. staphylococcal conjunctivitis<br />
3. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
Orbital cellulitis:<br />
a. may be secondary to dacrocystitis<br />
b. may be secondary to sinusitis<br />
c. is usually viral in origin<br />
d. may present with proptosis, reduced<br />
ocular movements and optic nerve<br />
compression<br />
4. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
Floaters in <strong>the</strong> field of vision:<br />
a. are always associated with peripheral<br />
visual disturbance<br />
b. may be caused by a posterior<br />
vitreous detachment<br />
c. always require pupil dilation and<br />
comprehensive retinal examination<br />
d. may be caused by posterior uveitis<br />
5. Which one of <strong>the</strong> following<br />
statements is correct?<br />
a. Bilateral homonymous hemianopia in<br />
<strong>the</strong> central 15 degrees of vision may<br />
be caused by a temporal lobe<br />
cerebro vascular accident (CVA,<br />
stroke)<br />
b. Left superior homonymous<br />
quadrantanopia may be caused by a<br />
CVA in <strong>the</strong> right temporal lobe<br />
c. Superior altitudinal field loss in one<br />
eye may be due to a superior branch<br />
retinal artery occlusion<br />
d. Transient ischaemic attacks (TIAs)<br />
affecting <strong>the</strong> tip of <strong>the</strong> occipital lobe<br />
may leave a residual field defect<br />
affecting only <strong>the</strong> central visual field<br />
6. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
Alkali injury:<br />
a. causes <strong>the</strong> pH of intraocular fluids to<br />
fall within seconds of injury<br />
b. should be irrigated with at least 1 litre<br />
of saline or water<br />
c. is potentially more serious than an<br />
equivalent acid injury<br />
d. More serious injury may be<br />
presumed if <strong>the</strong>re is substantial<br />
epi<strong>the</strong>lial loss and ischaemia of <strong>the</strong><br />
limbal vessels in <strong>the</strong> acute phase.<br />
7. Which one of <strong>the</strong> following<br />
statements is correct?<br />
In anterior uveitis:<br />
a. mutton fat keratic precipitates do not<br />
require investigation for associated<br />
systemic conditions<br />
b. systemic immunosuppression is<br />
always required to allow adequate<br />
control of inflammation in <strong>the</strong><br />
long-term<br />
c. intraocular pressure can rise during<br />
acute attacks<br />
d. always gives rise to symptoms of<br />
red eye, photophobia and reduced<br />
vision<br />
8. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
The acute management of<br />
central retinal artery<br />
occlusion may include:<br />
a. urgent ESR and CRP<br />
b. anterior chamber paracentesis<br />
c. intravenous acetazolamide<br />
d. isovolaemic haemodilution<br />
9. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
Optic nerve compression:<br />
a. may be caused by thyroid eye<br />
disease<br />
b. causes reduction in sensitivity to red<br />
target late in disease<br />
c. causes loss of acuity late in<br />
disease<br />
d. is usually associated with<br />
increasing pain and reduction in<br />
ocular motility<br />
10. Which one of <strong>the</strong> following<br />
statements is correct?<br />
Relative afferent pupillary<br />
defect:<br />
a. is a feature of homonymous<br />
hemianopia<br />
b. is a common feature of a peripheral<br />
retinal detachment<br />
c. is always symptomatic<br />
d. may be present in an eye with a<br />
normal visual acuity<br />
11. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
Retinal detachment:<br />
a. is associated with vitreous<br />
haemorrhage<br />
b. is associated with posterior vitreous<br />
detachment<br />
c. may cause visual field loss<br />
d. causes early loss of acuity<br />
12. Which one of <strong>the</strong> following<br />
statements is incorrect?<br />
In central retinal artery occlusion,<br />
temporal arteritis:<br />
a. is associated with jaw claudication<br />
and proximal myopathy<br />
b. may have a good visual recovery<br />
if adequate treatment is given rapidly<br />
c. may require a biopsy<br />
for a satisfactory diagnosis<br />
to be made<br />
d. requires treatment with steroids<br />
for a year or more<br />
sponsored by<br />
Multiple choice answers<br />
Here are <strong>the</strong> correct answers to Part 3 of<br />
Module 1 on Clinical Decision Making,<br />
published on March 12, 1999.<br />
1. Which one of <strong>the</strong> following statements is correct<br />
regarding <strong>the</strong> symptoms and signs found in a<br />
posterior vitreous detachment (PVD)?<br />
a. Flashing lights signify a definite retinal tear<br />
b. Floaters and flashing lights are more serious than<br />
floaters alone<br />
c. Pigment cells in <strong>the</strong> anterior vitreous indicate a high<br />
risk of retinal pathology<br />
d. Floaters always signify a posterior vitreous<br />
detachment<br />
c is correct<br />
In a posterior vitreous detachment, <strong>the</strong> presence or<br />
absence of flashing lights, in addition to <strong>the</strong> floaters,<br />
makes no difference with regards to risk of a retinal tear.<br />
Few symptoms may indicate serious pathology.<br />
Examination of <strong>the</strong> anterior vitreous as it moves may<br />
indicate pigmented cells (Schaeffer’s sign) which are<br />
strongly suspicious of a retinal tear, or o<strong>the</strong>r cells<br />
suggesting inflammatory eye disease as <strong>the</strong> cause of<br />
floaters.<br />
2. Which one of <strong>the</strong> following<br />
statements is correct regarding central<br />
retinal vein occlusion (CRVO)?<br />
a. Sources of emboli need to be excluded<br />
b. May be caused by hypertension<br />
c. Requires urgent fluorescein angiography<br />
d. Often recovers good visual acuity if treated with<br />
pan-retinal photocoagulation<br />
b is correct<br />
Hypertension is <strong>the</strong> commonest association with a<br />
CRVO. O<strong>the</strong>r associations include elevated intraocular<br />
pressure and prothrombotic tendencies. Emboli cause<br />
arterial ra<strong>the</strong>r than venous occlusions. Fluorescein<br />
angiography may help determine if <strong>the</strong> CRVO is<br />
ischaemic or not, but is not urgent as <strong>the</strong> haemorrhages<br />
may obscure <strong>the</strong> fluorescence acutely and<br />
neovascularisation does not occur immediately. Visual<br />
prognosis after a CRVO is often poor.<br />
3. In <strong>the</strong> management of age-related macular<br />
degeneration (ARMD), which one of <strong>the</strong><br />
following statements is correct?<br />
a. Hard macular drusen signify high risk of sub-retinal<br />
neovascularisation<br />
b. Geographic atrophy requires argon laser<br />
photocoagulation<br />
c. Sudden metamorphopsia requires urgent referral<br />
d. Low vision aids do not benefit patients with<br />
sub-retinal neovascularisation<br />
c is correct<br />
Dry ARMD (drusen, pigmentary changes and<br />
geographic atrophy) is treated conservatively. It is<br />
known that large soft drusen carry a higher risk of subretinal<br />
neovascularisation, of which <strong>the</strong> earliest sign may<br />
be metamorphopsia. Urgent referral is required if a<br />
patient develops this for consideration of laser or o<strong>the</strong>r<br />
treatment. Patients at all stages of ARMD may benefit<br />
from low vision aids.<br />
4. Which one of <strong>the</strong> following statements is<br />
correct?<br />
Branch retinal artery occlusion (BRAO) -<br />
a. is a result of arteriovenous nipping<br />
b. is caused by chronic open angle glaucoma<br />
c. always results in loss of central vision<br />
d. is often due to an embolus<br />
d is correct<br />
10<br />
APRIL 9 • 1999 OPTOMETRY TODAY
sponsored by<br />
Clinical decision making in ophthalmic emergencies<br />
DISTANCE LEARNING MODULE 1 PART 4<br />
- Clinical management of retinal disorders<br />
A BRAO is usually <strong>the</strong> result of an embolus,<br />
ei<strong>the</strong>r from <strong>the</strong> carotid or cardiac circulation.<br />
AV nipping may result in a branch retinal vein<br />
occlusion as <strong>the</strong> hypertrophic artery wall<br />
compresses <strong>the</strong> vein as <strong>the</strong>y cross, and open<br />
angle glaucoma is a risk factor for a central<br />
retinal vein occlusion. The artery occlusion<br />
may affect central vision if it supplies <strong>the</strong><br />
macula, or may cause field loss if it supplies<br />
ano<strong>the</strong>r part of <strong>the</strong> retina.<br />
5. Which one of <strong>the</strong> following<br />
statements is correct?<br />
Epi-retinal membrane -<br />
a. always requires surgical correction<br />
b. may cause metamorphopsia<br />
c. is more common in men aged 20-45<br />
d. is always idiopathic<br />
b is correct<br />
An epiretinal membrane may cause<br />
metamorphopsia. It may be idiopathic,<br />
affecting people of both sexes in <strong>the</strong>ir 50s and<br />
60s, or be due to o<strong>the</strong>r retinal problems such<br />
as post retinal detachment surgery and<br />
cryo<strong>the</strong>rapy. It often stabilises and, <strong>the</strong>refore,<br />
may require no treatment.<br />
6. Which one of <strong>the</strong> following retinal<br />
disorders does not present with<br />
floaters?<br />
a. Toxoplasmosis<br />
b. Posterior vitreous detachment<br />
c. Amaurosis fugax<br />
d. Intermediate uveitis<br />
c is correct<br />
The causes of floaters include a posterior<br />
vitreous detachment and inflammatory eye<br />
disease, such as toxoplasmosis and<br />
intermediate uveitis affecting one or both eyes.<br />
Amaurosis fugax causes a transient loss of<br />
vision lasting up to 10 minutes, affecting one<br />
eye.<br />
7. Which one of <strong>the</strong> following<br />
statements is correct regarding<br />
<strong>the</strong> management of retinal tears?<br />
a. A retinal tear associated with a retinal<br />
detachment will always be treated with<br />
argon laser only<br />
b. There is always a single retinal tear<br />
after a posterior vitreous detachment<br />
c. Retinal tears may be anterior to <strong>the</strong><br />
equator and not visible on slit lamp<br />
biomicroscopy<br />
d. Retinal tears are not treated with<br />
cryo<strong>the</strong>rapy<br />
c is correct<br />
Retinal tears in association with a posterior<br />
vitreous detachment may be anterior to <strong>the</strong><br />
equator of <strong>the</strong> retina and require indirect<br />
ophthalmoscopy with indentation to see. They<br />
may be multiple and can be treated with laser<br />
or cryo<strong>the</strong>rapy. However, if <strong>the</strong>re is an<br />
associated retinal detachment, laser is usually<br />
inadequate and <strong>the</strong>y require detachment<br />
surgery to flatten <strong>the</strong> detachment and to allow<br />
<strong>the</strong> laser or cryo<strong>the</strong>rapy to ‘seal’ <strong>the</strong> tear.<br />
8. Which one of <strong>the</strong> following<br />
statements is correct?<br />
Macular holes -<br />
a. affect men more commonly than<br />
women<br />
b. may be bilateral<br />
c. require laser treatment<br />
d. often follow on from retinal detachment<br />
surgery or cryo<strong>the</strong>rapy<br />
b is correct<br />
Macular holes typically affect postmenopausal<br />
women and are said to be<br />
bilateral in 10%. They are usually primary or<br />
idiopathic (that is not associated with o<strong>the</strong>r<br />
retinal disease) and may require surgery in<br />
<strong>the</strong> form of vitrectomy and intraocular gas<br />
injection to flatten <strong>the</strong>m.<br />
9. Which one of <strong>the</strong> following<br />
statements is correct?<br />
Acute central retinal artery occlusion -<br />
a. is treated with intravenous steroids<br />
b. requires attempts to lower <strong>the</strong> intraocular<br />
pressure<br />
c. always requires laser treatment to prevent<br />
neovascularisation<br />
d. subsequently results in a cupped optic<br />
disc<br />
b is correct<br />
Treatment for a central retinal artery occlusion<br />
is often disappointing, but attempts are made<br />
to move <strong>the</strong> embolus down <strong>the</strong> arterial tree by<br />
acutely lowering <strong>the</strong> intraocular pressure<br />
using ocular massage and intravenous<br />
acetazolamide (diamox). It does not require<br />
laser treatment (unless rubeosis occurs) and<br />
usually results in optic atrophy and severely<br />
reduced vision.<br />
10. Which one of <strong>the</strong> following<br />
statements is correct?<br />
Photopsia (flashing lights) -<br />
a. last less than 10 minutes in a migraine<br />
attack<br />
b. are usually bilateral in migraine<br />
c. are homonymous in posterior vitreous<br />
detachment<br />
d. are associated with o<strong>the</strong>r symptoms in<br />
vertebrobasilar disease<br />
b is correct<br />
Photopsia in migraine last 10-30 minutes and<br />
are usually homonymous and, <strong>the</strong>refore,<br />
affect both eyes even though most patients<br />
will describe <strong>the</strong>m as unilateral. In posterior<br />
vitreous detachment, <strong>the</strong>y are unilateral and<br />
occur as flickers lasting a few seconds just in<br />
<strong>the</strong> temporal field of vision in dim light.<br />
Photopsia are not usually associated with<br />
vertebrobasilar disease and would occur with<br />
o<strong>the</strong>r symptoms such as vertigo and drop<br />
attacks.<br />
11. Which one of <strong>the</strong> following<br />
statements is correct regarding<br />
hypertensive retinal<br />
changes?<br />
a. Venous beading and venous<br />
looping are signs of accelerated<br />
hypertension<br />
b. AV nipping occurs as a result of<br />
hypertrophy of <strong>the</strong> vein wall due<br />
to <strong>the</strong> hypertension<br />
c. Swollen discs, haemorrhages and<br />
exudates indicate a dangerous<br />
level of blood pressure<br />
d. Silver-wiring is <strong>the</strong> earliest sign<br />
of hypertension<br />
c is correct<br />
Accelerated hypertension, in which swollen<br />
discs, haemorrhages, cotton wool spots and<br />
exudates are seen, indicates a sudden<br />
severe elevation in blood pressure and<br />
patients require urgent admission for<br />
treatment and to establish <strong>the</strong> cause, which is<br />
often renal disease. The changes of chronic<br />
essential hypertension include narrowed and<br />
straightened arterioles and AV nipping in<br />
which <strong>the</strong> thickened artery wall compresses<br />
<strong>the</strong> vein as <strong>the</strong>y cross. Silver-wiring is not a<br />
good sign of hypertension.<br />
12. Which one of <strong>the</strong> following does not<br />
require laser treatment?<br />
a. A retinal hole<br />
b. Central retinal vein occlusion<br />
c. Branch retinal artery occlusion<br />
d. Sub-retinal neovascular<br />
membrane<br />
c is correct<br />
Argon laser photocoagulation may be<br />
required to seal around a retinal tear or hole,<br />
to ablate a sub-retinal neovascular membrane<br />
or to prevent rubeosis with pan-retinal<br />
photocoagulation in an ischaemic central<br />
retinal vein occlusion. It is not normally<br />
required in a branch retinal artery occlusion<br />
as <strong>the</strong> retina distal to this is infarcted, not<br />
ischaemic.<br />
APRIL 9 • 1999 OPTOMETRY TODAY 11